Electric switch mechanism



Oct. 13, 1942. v. W.LEONARD ELECTRIC SWITCH MECHANISM Filed Dec. 24,1940 RE b \QMJ w Inventor: Vincent W. Leonard, y W 6 x/M M His Attorney.

Patented Oct. 13, 1942 ELECTRIC SWITCH MECHANISM Vincent W. Leonard,Saugus, Mass., assignor to General Electric Company, a corporation ofNew York Application December 24, 1940, Serial No. 371,494 1 Claim. (01.200-1) My invention relates to an electric switch mechanism and moreparticularly to a switch mechanism provided with switch contact arms ofthe resilient blade type.

One object of my invention is to provide an improved switch mechanismprovided with a resilient switch contact arm which may be readilyadjusted to regulate the operating pressure between a contact tipcarried by the arm and a cooperating contact tip.

Another object of my invention is to provide an improved switchmechanism provided with a resilient contact arm the fiexure of whichcontact arm may be adjusted to regulate the force required to actuatethe contact arm for switching operations.

For a better understanding of my invention, together with other andfurther objects thereof, reference is had to the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

In the accompanying drawing I have chosen to illustrate my invention byway of example, as applied to a switch mechanism used in traf fic signalcontrollers. Fig. l of the drawing illustrates a switch mechanismincluding a group of switch contact arms mounted in a single block ofinsulation and actuated by actuating fingers or keys mounted in arotating dial; Fig. 2 is a rear perspective view of the contact blockillustrated in Fig. 1, and Fig. 3 is a cross-sectional view of thecontact block illustrating, in side view, the mechanism in the block.

Referring to the drawing in detail, the switch mechanism illustratedincludes a block ill of a suitable insulating material having agenerally rectangular shape provided with a slot open on one side and atthe ends of the block. Three pairs of switch contact arms I'I, I2; l3,l4; and I5, I6 extend through this block from end to end, being placedinto the slot through the open side thereof. The pairs are arranged sideby side and the contact arms of a pair are arranged above one another.

The contact arms are made of a metal strip which is preferably bronze orhard copper. They are mounted rigidly at one end and are provided withcontact trips at their free ends which are given a limited range ofmovement. Such metal strips have the characteristic of being flexible toa degree, in the manner of a spring steel blade, without permanentlylosing shape. In other words, a strip of this metal may be held movedfor a considerable degree out of line with its normal position and, whenreleased, it will spring back to its original position. The forcerequired to flex such a strip increases with the distance by which theend of the spring is displaced from its original position, whereby arange of contact pressures may be obtained by regulating the amount ofinitial flexure of the strip.

The front ends of the upper contact arms. which project out of the blockIn at the front end are bent backwardly to form hooks I1, I 3 and IS,the ends of which hooks engage a pro- Jecting ledge or stop 20 at theforward upper end of the block. The hooked ends I1, l8 and [9 rest uponthis ledge 20 to stop the downward movement of the contact arms. Thehooks are so proportioned as to leave a considerable space between theunder side of the ledge 20, which is a continuation of the slot surface,and the upper side of the contact arm, this space providing the range ofmovement of the forward end of the contact arm.

The forward end of eachof the lower contact arms I 2, l4 and I6 is bentdownwardly at right angles to the body of the arm and is provided withan actuating block. A block 2| is attached to the contact arm l2, ablock 22 is attached to the contact arm I! and a block 23 is attached tothe arm It. The actuating blocks 22, 23 are of equal length but areconsiderably shorter than the actuating block 2|.

The contact arms are each supported at the back end of the block by asoft metal member 3i. This supporting member 3| is made of anonresilient and comparatively soft metal such as copper, for example.In the illustrated switch mechanism this member is bent at the center toform two legs 32 and 32 meeting at an apex at substantially right anglesto each other. One leg 32 is provided with holes so that it may beattached to the end of the block I'll. This leg is attached to the endof the block by screws 33 so that the other leg 32' projects away fromthe end of the block. This leg 32' has attached to it the back endportion of the resilient contact arm. Any convenient method of attachingthe arm may be used. In the illustrated examrigidly at one end and theother end may be ple the arm is attached by being soldered to the leg32. The arm then projects through the slot to the other end of theblock, parallel to the surface of the slot and slightly spacedtherefrom.

After a set of contacts is mounted in an insulating block as shown inthe drawing, the projectlng leg 32' of each member 3| may be sepaforwardend of the block Ill which forms a stop for the contact arm, and maythen be" bent further to flex the contact arm until a certain pressurewill be required to move this forward end upwardly, this pressure beinglarge enough to prevent the forward end of this contact arm fromvibrating as a resultof ground vibrations set up, for instance, by heavytrafiic. The force required to move the arm must be small enough theblock 23 nearest to the dial and the key 25, having therein a slot 25',passes the block 23 and actuates the block 22. The block 2| is actuatedby a key 29 placed in an inner row of slots 30 so as not toplace toogreat a load upon the actuating mechanism. Similarly, the leg 32'supporting the contact arm ll may be bent so that the forward end of thecontact arm I! will move downwardly and its hook l1 will engage theupper side of the ledge 26. The leg may then be bent further to flex thecontact arm so that the hook will engage the ledge with some pressureand will not vibrate. During operation,

' when the contact arm I2 is actuated, the contact arm moves upwardlyuntil its contact tip l2 engages the contact tip ll" of the arm H. Inorder to insure a good contact, in each instance, the engagement of thecontact tips occurs before the end of the movement of the contact arml2. It is therefore necessary to overcome the flexing resistance of botharms H and I2 for the last part of the actuation or movement of thecontact tip I2. In order'to require a minimum actuating force, thefiexure of the two contact arms must therefore be reduced to a minimumconsistent with the tendency of the contact arms to vibrate andconsistent with the needed pressure between the contact tips duringengagement. v o

The other contacts in the block ID are similarly provided with L memberswhereby their positionscan be individually adjusted with the aid ofsuitable pliers being applied to the rearwardly projecting arms 32' oftheir respective L members. This improved mounting of the contact fingerenables an operator to mount all contact arms within a single block andthen individually adjust the fiexure and alinement of each contactwithout removing a single one from the block.

One method of actuating the contact arms of my improved switch mechanismis illustrated in Figs. 1 and 3. The blocks 2|, 22 and 23 are thereinactuated by keys placed in a rotating dial. The short blocks 22 and 23are actuated by keys 24 and 25 placed in an outer row of slots 26 of therotating dial 21. The key 24 actuates on the dial 2]. Each of the blocks2|, 22 and 23 is provided with an end surface arranged at such anglethat during the clockwise rotation of the actuating keys 24, 25 and 29they respectively engage the surfaces and effect an upward motion of theblocks during the circular motion of the keys. During such operation theblock 2|, for example, is lifted upwardly by the key 29, thereby movingthe forward end of the contact arm |2 upwardly so that the contact tipi2 mounted at the forward end of the contact arm engages the cooperatingcontact tip ii mounted on the underside of the contact arm therebyefiecting a circuit closure between this pair of contact arms. Similarcontact tips are mounted opposite each other upon the other two pairs ofcontact arms and similarly the keys 24 and 25 engage and move upwardlythe blocks 23 and 22 respectively to effect a circuit closure betweenthe contact tips of these two pairs of contactarms.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

In a switch mechanism, the combination of an insulating block providedwith a slot and a ledge at one end of said slot, a pair of L memberseach L member comprising two legs projecting from an apex in angularrelationship to each other one of said legs being attached to the end ofsaid block with the second leg projecting away from the end of saidblock at one end of said slot said projecting legs being spaced fromeach other and arranged above one another, a resilient switch contactarm attached at one end to the upper one of said second legs projectingthrough said slot and provided with a hook at its free end for engagingsaid ledge at the other end of said slot said second leg beingadjustable about its apex to effect an engagement of said hook end ofsaid contact with the said ledge and upon further adjustment to efiect afiexure of said contact arm to establish a predetermined resistance toa, movement away from said ledge, a second contact arm attachedto thelower pro- J'ecting leg said contact arm also projecting through saidslot and being arranged to cooperate with said first-mentioned contactarm said lower second leg being adjustable about its apex to move saidfree end of said contact arm against the side of said slot and tofurther move said contact arm to efiect a predetermined 'flexure of saidarm thereby to establish a predetermined resistance to actuation of saidlast-mentioned arm, and means arranged to intermittently actuate saidcontact arms.

VINCENT W. LEONARD.

